This invention relates to a projector for projecting and displaying images.
Projectors display images by modulating light from an illumination optical system in response to image information (image signal) by a liquid crystal light valve, and projecting the modulated light onto a screen.
The liquid crystal light valve generally includes a liquid crystal panel and polarizing plates arranged on a light incident side and a light exiting side of the liquid crystal panel. The polarizing plate functions to allow transmission of only a light component in the direction of a polarization axis, while cutting off the other light components. The light entering the liquid crystal light valve is thus modulated in response to image information.
The polarizing plate generates heat during cutting off the light other than the light component in the direction of the polarization axis. The generated heat raises the temperature of the polarizing plate and causes distortion and deterioration of the polarizing plate. The distorted and deteriorated polarizing plate mistakenly allows transmission of non-target light while cutting off non-target light. The polarizing plate is conventionally attached to a glass plate like crown glass called white plate glass. But recently, the polarizing plate is attached to a sapphire substrate having a relatively high thermal conductivity, so as to suppress the temperature rise of the polarizing plate.
Manufacture of the sapphire substrate is, however, relatively difficult, which makes it rather difficult to manufacture the projector. This is ascribed to difficulties in production and processing of sapphire. This problem is common to all the projectors utilizing the sapphire member.
The object of the present invention is thus to solve the drawbacks of the prior art discussed above and to provide a technique of readily manufacturing a projector.
At least part of the above and the other related objects is attained by a first apparatus of the present invention, which includes: an illumination optical system for emitting light; an electro-optical device for modulating the light emitted from the illumination optical system in response to image information; a projection optical system for projecting a modulated light generated by the electro-optical device; and an optical component having a rock crystal member composed of rock crystal, the optical component being located in an optical path including the illumination optical system and the projection optical system.
The first apparatus of the present invention has the optical component including the rock crystal member composed of rock crystal. The rock crystal member is more easily manufactured than the conventionally used sapphire member. This facilitates manufacture of the optical component including the rock crystal member and thereby manufacture of the projector. Rock crystal has a higher thermal conductivity than the conventionally used glass. Another advantage is thus to suppress a temperature rise of the optical component.
In one preferable application, the rock crystal member is disposed in such a manner that a Z axis of the rock crystal is substantially perpendicular to a center axis of a light passing through the rock crystal member.
In rock crystal, the thermal conductivity of a plane parallel to the Z axis is higher than the thermal conductivity of a plane perpendicular to the Z axis. The above arrangement thus further suppresses the temperature rise of the optical component and homogenizes an in-plane temperature distribution in a face perpendicular to the center axis of the light.
In this application, when the light passing through the rock crystal member is linearly polarized light, it is preferable that the rock crystal member is disposed in such a manner that the Z axis of the rock crystal is substantially parallel to or substantially perpendicular to an electric vector of the linearly polarized light.
This arrangement effectively ensures little variation in polarizing state when the linearly polarized light passes through the rock crystal, which is an optically uniaxial crystal.
In another preferable application, the rock crystal member is disposed in such a manner that a Z axis of the rock crystal is substantially parallel to a center axis of a light passing through the rock crystal member.
However, the polarizing state of light varies when the center axis of the light passing through the rock crystal member is not sufficiently parallel to the Z axis of the rock crystal. It is accordingly preferable that such a rock crystal member is disposed at a position that hardly utilizes specified polarized light such as the linearly polarized light or at a position that is hardly affected by the variation in polarizing state.
In one preferable embodiment of the above apparatus, the optical component has: a rock crystal substrate as the rock crystal member; and an optical element provided on the rock crystal substrate, and a Z axis of the rock crystal substrate is set to be substantially parallel to a surface of the substrate.
In this case, the heat of the optical element is transmitted parallel to the surface of the rock crystal substrate. This further suppresses the temperature rise of the optical component and homogenizes an in-plane temperature distribution of the optical component.
In this embodiment, it is preferable that the optical element is a polarizing plate, and the polarizing plate is provided on the rock crystal substrate in such a manner that a polarization axis of the polarizing plate is substantially parallel to or substantially perpendicular to a Z axis of the rock crystal.
In this arrangement, when the light output from the polarizing plate enters the rock crystal substrate, the polarizing state of the linearly polarized light output from the polarizing plate will be kept. On the other hand, when the light output from the rock crystal substrate enters the polarizing plate, only a predetermined linearly polarized light will be output by means of the polarizing plate. In the latter case, when the linearly polarized light enters the rock crystal substrate, the incident linearly polarized light will enter the polarizing plate with little variation in polarizing state.
In another preferable embodiment of the above apparatus, the optical component has: a rock crystal substrate as the rock crystal member; and an optical element provided on the rock crystal substrate, and a Z axis of the rock crystal substrate is set to be substantially perpendicular to a surface of the substrate.
However, the polarizing state of light varies when the center axis of the light passing through the rock crystal member is not sufficiently parallel to the Z axis of the rock crystal. It is accordingly preferable that such a rock crystal member is disposed at a position that hardly utilizes specified polarized light such as the linearly polarized light or at a position that is hardly affected by the variation in polarizing state.
In the above apparatus, it is preferable that the electro-optical device has a pair of substrates, at least one of the pair of substrates is a rock crystal substrate as the rock crystal member, and a Z axis of the rock crystal substrate is set to be substantially parallel to or substantially perpendicular to a surface of the substrate.
This arrangement effectively suppresses a temperature rise of the electro-optical device.
In the above apparatus, the rock crystal member may be a lens.
This arrangement effectively suppresses a temperature rise of the lens. In the structure that another optical element is attached to or arranged close to the lens, a temperature rise of the optical element will be also suppressed.
In one preferable application of the above apparatus, the illumination optical system may include a polarized light generation section for emitting a predetermined polarized light. The polarized light generation section may include: the optical component for dividing an incident light into two different polarized lights; and a selective retardation plate for adjusting one of the two polarized lights output from the optical component to the other. The optical component may include: a plurality of the rock crystal members arrayed in a predetermined direction; and a polarization separation film and a reflection film that are alternately arranged on interfaces of the plurality of rock crystal members.
In another preferable application of the above apparatus, the illumination optical system may include a polarized light generation section for emitting a predetermined polarized light. The polarized light generation section may include: the optical component for dividing an incident light into two different polarized lights; and a selective retardation plate for adjusting one of the two polarized lights output from the optical component to the other. The optical component may include: the rock crystal member; and a polarization separation film formed on the rock crystal member.
Either of the above applications desirably suppresses a temperature rise of the optical component. In the structure that a retardation plate is attached to the optical component, a temperature rise of the retardation plate will be also suppressed.
The present invention is also directed to a second apparatus, which includes: an illumination optical system for emitting light; a color light separation optical system that divides the light emitted from the illumination optical system into first through third color lights respectively having three color components; first through third electro-optical devices that modulate the first through the third color lights divided by the color separation optical system in response to image information, so as to generate first through third modulated lights; a color light composition optical system for combining the first through the third modulated lights; a projection optical system for projecting composite light output from the color light composition optical system; and an optical component having a rock crystal member composed of rock crystal, the optical component being located in an optical path including the illumination optical system and the projection optical system.
The second apparatus of the present invention has the optical component including the rock crystal member composed of rock crystal and thereby exerts the similar functions and advantages to those of the first apparatus.
In one preferable application of the above apparatus, at least one of the color light separation optical system and the color light composition optical system may include the optical component. The optical component may include: the four columnar rock crystal members divided by a substantially X-shaped interface; and a selector film formed on the interface to select light having wavelength in a predetermined range.
In another preferable application of the above apparatus, at least one of the color light separation optical system and the color light composition optical system may include the optical component. The optical component may include: the rock crystal member; and a selector film formed on the rock crystal member to select light having wavelength in a predetermined range.
These arrangement desirably suppresses a temperature rise of the optical component. Especially when an optical element, such as a polarizing plate or a retardation plate, is attached to the optical component, the arrangement also suppresses a temperature rise of the optical element.